HP Z420 CPU fan error

[BogdanP1]

I appreciate your help but please bear with me, I don't have experience with computer parts, that's why I have a workstation, otherwise I would've built my own computer from parts. Hope this is the picture you requested.

[BogdanP1]

I don't think it ships to Romania cause I don't see any image that resembles the part in what you sent.

[DGroves]

the wiring on the fan indicates by it's colors that it is indeed a std "PWM" fan and the 4 pwm wires appear to go to a small circuit board that has the 5 black wires going to the 5 pin connector is this correct?

if so all you need to do is  cut the 4 colored wires on the failing fan as close to the fan label as possible and then match the colored wires to the replacement fan (cutting off the existing 4 pin connector) and tape/heat shrink the connections up

here's a amazon link to the fan you need

https://www.amazon.com/EVERFLOW-F129025SU-0-38A-8holes-Cooling/dp/B00JK7YUGY

and eBay link for a NEW old stock one 

https://www.ebay.com/itm/171187242900

[BogdanP1]

Yes, you are correct. But how do you know the fan is the one that's broken? When I force start the computer and the 511 error is shown, the fan is still spinning as usual, couldn't it be the liquid cooling pump that is broken instead?

[DGroves]

if you had simply taken the time to use this forum's "SEARCH" feature using  keywords "hp z420 511 error"

you could have answered your question yourself

i suspect the fan is not spinning at the proper speed, or failing to spin at random time for a period of time

z420 https://h30434.www3.hp.com/t5/Desktops-Archive-Read-Only/511-CPU-FAN-not-detected-but-fan-is-blowing...

yes, it's possible the pump has failed, this is why replacing the ENTIRE unit is strongly recommended

here's just the HP Fan (amazon)

https://www.amazon.com/Comp-XP-Genuine-Workstation-653905-001/dp/B07DNFV77F

and here's the entire unit for almost the same price (USA seller)

https://www.ebay.com/itm/304282441070?hash=item46d8a5956e:g:1BAAAOSwIchhzXNA

[BogdanP1]

I did take the time to search, I know how to use the internet... It's that this component differs from the one that most of the topics describe, as is the case with the link you sent, where somebody asks the question about the liquid cooling variant.

Again, I'm not that experienced with these parts and I thought "fan" refers to the whole assembly, wasn't even aware that I could separate the actual fan from the whole piece without breaking anything in the process.

Thanks for the help though and sorry to have bothered you with my lack of knowledge.

[DGroves]

this sites "SEARCH" link should be displayed more prominently in my opinion but that's hp's call to make as they own this site and all forums on it

The same results can almost always be duplicated or even enhanced using a web search engine like "google"

knowing how to search, and knowing how to search efficiently are two very different things..... i know most people already have very busy lives, but if you can find the fime google "how to search the internet efficiently" and read some of the many links, they may possibly prove useful in the future

https://www.google.com/search?q=how+to+search+the+internet+efficiently&rlz=1C1SQJL_enUS909US909&sour...

[SDH]

We feel your pain.  Z420 workstations can run with water cooling or with fan/heatsink cooling, as you know.  The electrical and mechanical features of water cooling are more complex... more to go wrong.

The next generation HP workstation, the Z440, runs on the version 3 or version 4 processors while the Z420 runs on version 1 or version 2 of the same family of processors.  HP increased the cooling capacity of their fan/heatsink combination for the Z440 with a bigger better unit, which you can see by searching eBay for 749554-001.  There are a lot of them available now that the Z440 workstations are being parted out, and they cool about twice as well as the original heatsink/fan used in the Z420.  HP makes no water cooler for the Z440 as a result.  I have been able to buy these off eBay for as low as $15.00 USD including shipping, but generally about $20.00.

That 749554-001 unit has double the cooling fin surface area and more/bigger cooling heat tubes.  I've been using those in our fastest single-processor Z620 and Z420 builds.  They work perfectly as is.  Your motherboard will automatically recognize and work with this unit.  This is a known solution that works... don't use a non-HP Noctua heatsink/fan(s) alternative because the PWM control coming from the HP motherboard will slow those fan(s) too much.

This all works well because the Z440's socket has exactly the same mechanical dimensions as that used for the Z420 socket.  The pinout at the bottom surface of the socket is different, which is engineered for v3 and v4 processors, but the stainless socket above is identical. Search for that number in the forum here and you'll see info on this plug-and-play solution.  It fits perfectly inside every Z420... and also fits in all our Z620 single processor builds.  I do recommend use of the Noctua original thermal paste NT-H1 because of how well it spreads on the processor's top stainless surface.  Clean first with a damp (but not wet) paper towel using  isopropyl alcohol.  No drops should be released from the paper towel as you clean. Repeat with fresh damp paper towel as needed.  You want the processor's top surface and the new heatsink's bottom surface free of old thermal paste.  I assume you know how careful you need to be with removing and replacing the processor.  I fold up a fresh dry paper towel to 1/4 size and set the bottom surface of the processor on that during cleaning so no excess pressure is placed on the little resistors projecting from the under-surface of the processor.

The fan for this 749554-001 heatsink has a 6-hole white plug end.  The Z420 has a 5-pin motherboard header, so you just attach that plug with pin 6 sitting off to the side of the header and use only the pins 1-5 holes of the white plug.  I show that in some of my posts... I used to swap out the fan but that is not needed once I came up with this solution.  The pinout is standard PWM for pins 1-4.  HP added to that a long ground jumper wire from hole 1 to hole 5.  The 6th hole is simply for another short ground jumper wire from hole 5 to hole 6.  Holes 1,5, and 6 are all connected as a result.  Thus, electrically hole 6 is not needed to be used on the Z420/Z620 motherboard's 5-pin CPU cooling header.

Your Z420 motherboard will be happy, and so will you.